Hitherto, electrochromic devices (hereinafter referred to as “EC devices”) have been known as devices such as light adjusters having a light adjusting capability of enabling the transmissivity to be freely adjusted (hereinafter referred to as “light adjusting devices”). Such an EC device is, for example, made from a material that undergoes a spectral change upon an electrochemical redox reaction, such as tungsten oxide or prussian blue, and controls the transmitted light by absorbing light. However, because such an EC device is current driven, if the EC device is made to have a large area, then a large voltage drop arises, the response speed drops markedly, and degradation of constituent materials due to electrochemical changes and so on occurs during prolonged passing of a current; such an EC device thus cannot be used as a light adjuster that is required to be durable.
In recent years, voltage driven light adjusting devices have thus been used in a laminated glass instead of such current driven EC devices. For example, nematic curvilinear aligned phase (NCAP) liquid crystal light adjusters are known as such voltage driven light adjusting devices. Such a nematic liquid crystal light adjuster is made from a liquid crystal material, and has excellent durability, and can easily be made to have a large area (see, for example, Japanese Laid-Open Patent Publication (Kohyo) No. S58-501631).
As shown in FIG. 2, in general, such a light adjuster 20 is comprised of a liquid crystal layer 23 having a light adjusting function in which a plurality of voids 21 are filled with nematic liquid crystalline rod-like molecules (hereinafter referred to as “liquid crystal molecules”) 22, and a pair of PET films 24 that sandwich the liquid crystal layer 23 therebetween; transparent electrically conductive films 25 are provided on facing surfaces of the PET films 24 so as to be bonded to the liquid crystal layer 23, and a voltage is applied to the liquid crystal layer 23 via this pair of transparent electrically conductive films 25. The liquid crystal layer 23 is formed of a transparent polymer film 26 having a plurality of voids 21 therein, and each void 21 is filled with liquid crystal molecules 22 so as to form a liquid crystal capsule 27.
According to this light adjuster 20, when a voltage is not being applied, the liquid crystal molecules 22 line up along the curved wall surfaces of the liquid crystal capsules 27, and are thus not arranged along the direction of travel of light transmitted through the liquid crystal capsules 27; the optical path of the transmitted light thus meanders around, and incident light is scattered at boundary layers between the liquid crystal capsules 27 and the polymer film 26, and hence the liquid crystal layer 23 becomes cloudy. On the other hand, when a voltage is applied, the liquid crystal molecules 22 line up along the direction of the electric field produced. At this time, if the liquid crystal layer 23 is made from a material such that the ordinary refractive index no of the liquid crystal molecules 22 matches the refractive index np of the polymer film 26, it becomes such that boundary layers between the liquid crystal capsules 27 and the polymer film 26 do not exist optically, and hence light incident on the liquid crystal layer 23 can be transmitted unhindered, whereby the liquid crystal layer 23 becomes transparent.
Due to the above principle, the light adjuster 20 has a visual field controlling capability of shutting off the visual field through scattering of incident light when a voltage is not being applied, and securing the visual field through allowing incident light to be transmitted unhindered when a voltage is being applied. A laminated glass using such a light adjuster is employed in show windows or the like, as a laminated glass having a visual field controlling capability.
FIG. 3 is a sectional view of the schematic construction of a laminated glass using the light adjuster in FIG. 2.
In FIG. 3, a laminated glass 30 is comprised of a pair of glass sheets 31a and 31b that are disposed in facing relation to each other, transparent intermediate layers 32a and 32b provided on respective facing surfaces of the glass sheets 31a and 31b, and the light adjuster 20 that is sandwiched between the intermediate layers 32a and 32b. The light adjuster 20 has an electrode structure, described below, which is provided on a part of the transparent electrically conductive film 25b which is exposed with the liquid crystal layer 23, the transparent electrically conductive film 25a, and the PET film 24a being partially cut off.
This electrode structure includes a connecting base formed of a silver paste 33 that is applied to the exposed part of the transparent electrically conductive film 25b, and a copper tape 34 that is stuck on the upper surface of the silver paste 33, and a connector 35 in the form of a strip formed of a metallic mesh that is interposed between the copper tape 34 and the intermediate layer 32a and is soaked with solder. With the soaked solder being melted, the connector 35 becomes secured at one end thereof to the copper tape 34, and the other end becomes secured to the lead line 36 that supplies power from an external power source.
With the light adjuster 30, a part of the connector 35 is made to protrude from the periphery of the laminated glass 30 in order to secure connection of the connector 35 and the lead line 36. The part which protrudes, however, can freely bend and will not interfere with other parts. Therefore, the handleability of the laminated glass using the light adjuster can be improved.
However, in the above-described electrode structure, the connecting base and the connector 35 are formed of separate members. Consequently, the structure is complex, and there arises a problem that the labor time required to prepare the light adjuster 20 becomes extensive.
Further, since the connector 35 is soaked with solder, there is a possibility that cadmium is produced, which triggers environmental problems. In addition, since the connector 35 is secured to the copper tape 34 and its adjacent parts when the soaked solder is melt, it becomes necessary to heat the light adjuster 20, which causes a problem that the liquid crystal layer 23 of the light adjuster 20 degrades due to the heating.
The present invention has been devised in view of the above-described problems, and it is an object of the present invention to provide a light adjuster and a laminated glass which are capable of reducing labor time while suppressing production of cadmium and preventing degradation of the liquid crystal layer.